Non-prescribed use of stimulant medications among college students, such as methylphenidate (Ritalin(R)) and amphetamine (Adderall(R)), has become a public health concern. Expectancies, which are beliefs that individuals hold regarding the consequences of engaging in a particular behavior, such as drinking alcohol or using drugs, are known to play a prominent role in the initiation and maintenance of alcohol and drug use, including non-prescribed use of stimulant medication. Research has also shown that, by challenging an individual's expectancies about the effects of the use of alcohol, his or her expectancies can be modified which can lead to a reduction in use of alcohol. Given this, it is of great importance to determine if and how expectancies related to non-prescribed use of stimulant medication can be challenged in order reduce and/or stop the misuse of this drug. The long-term goal of this study is to develop an intervention that can be used to reduce and/or eliminate non-prescribed use of stimulant medications among traditional-aged undergraduate college students. This project has two specific aims. The first specific aim is to determine if an expectancy challenge can reduce participants'academic performance expectancies (e.g., stimulant medications will help you concentrate better) related to non-prescribed use of stimulant medications. The second specific aim is to determine if expectancies related to non-prescribed use of stimulant medication mediate consumption of the drug. Undergraduate college students will be recruited and randomized to an expectancy challenge (EC) condition, a psychoeducation (PE) condition, or an assessment-only (AO) condition. Students in the EC condition will undergo two brief cognitive testing sessions. During the second testing sessions participants will receive placebo Ritalin(R) and at the end of the session will be educated about expectancies and their role in the initiation and maintenance of drug use. Students in the PE condition will undergo the same procedures as participants in the EC condition;however they will not receive placebo medication. Finally, students in the AO condition will only undergo the two cognitive testing sessions. It is hypothesized that the expectancy challenge will significantly reduce academic performance expectancies related to non-prescribed use of stimulant medications and consumption of use, and that this reduction will be maintained over time. Further, it is hypothesized that change in expectancies will attenuate the relationship between the expectancy challenge and consumption of the medication at three months post- treatment. PUBLIC HEALTH RELEVANCE: The results from this study will be used to further our understanding of the mechanisms that mediate the relationship between non-prescribed use of stimulant medication and initiation and maintenance of use of this drug. Additionally, knowledge gained from this study can be used to create appropriate prevention and intervention programs aimed at reducing non-prescribed use of stimulant medication among college students.